1. Field of the Invention
The invention relates to a mobile camera implementation for a medical imaging device such as a gamma camera, and more particularly a device having fully enclosed one or more camera detectors that move within the device housing on rails.
2. Background Discussion
Single photon emission computed tomography (SPECT) imaging is performed by using a gamma camera to acquire image or projection data from multiple angles with respect to a patient. The data is then sent to a computer that applies a tomographic reconstruction algorithm to the multiple projections, yielding a 3D dataset, which can be used to generate tomographic images for display on a display device.
To acquire SPECT images the gamma camera is rotated around the patient with projections being acquired at defined points during the rotation, typically every 3-6 degrees. In most cases, a full 360 degree rotation is used to obtain an optimal reconstruction. The time taken to obtain each projection is also variable, but 15-20 seconds is typical giving a total scan time of 15-20 minutes.
Multi-headed gamma cameras can provide accelerated acquisition, e.g. a dual headed camera can be used with heads spaced 180 degrees apart, allowing 2 projections to be acquired simultaneously, with each head only requiring 180 degrees of rotation. Triple-head cameras with 120 degree spacing are also used.
Gated acquisitions are possible with SPECT, just as with planar imaging techniques such as multiple gated acquisition scans (MUGA). Cardiac gated myocardial SPECT can be used to obtain quantitative information about myocardial perfusion during the cardiac cycle, thickness and contractility of the myocardium and allow calculation of left ventricular ejection fraction, stroke volume, and cardiac output.
Computer tomography (CT) scanners use a fan shaped beam of x-rays that is directed to an array of detectors that are fixed in position relative to the x-ray source. In some models of CT devices the images are acquired by a “translate-rotate” method in which the x-ray source and the detector in a fixed relative position move across the patient followed by a rotation of the x-ray source/detector combination (gantry) by one degree. In other models, instead of a row of detectors that move with the X-ray source, a stationary 360 degree ring of detectors is provided. The fan shaped x-ray beam is rotated around the patient in a non-fixed relationship with respect to the stationary detectors.
Ultrasonography is a useful ultrasound-based medical imaging technology used for medical diagnostics. In addition to its diagnostic value, ultrasonography can be used to treat benign and malignant tumors and other disorders through focused ultrasound surgery (FUS) or high intensity focused ultrasound (HIFU).
Positron emission tomography (PET) is a nuclear medicine medical imaging technique that produces three dimensional images using a radioactive tracer isotope, and is based on the physical phenomenon whereby annihilation of a positron by collision with an electron results in the simultaneous emission of two gamma photons traveling in 180 degree opposed directions. The simultaneously emitted photons are detected by a pair of 180 degree opposed detectors within the camera unit, by detecting coincidence events.
The devices required for the above medical applications are generally large and extremely expensive. Some of the smaller devices run on gantry systems that are open exposing the patient to the moving cameras and mechanics. The size and/or or movement of the devices during the procedure can be intimidating to a patent, adding stress to an already stressful situation. To date, a simple enclosing of the gantry to eliminate motion is possible but sub-optimal for patient positioning. Additionally, enclosing the detector heads is costly, as the detector heads are usually suspended from a gantry or from an arm where the motion of the detectors is enabled by various trunions.